Matter Falling Into A Black Hole At 30 Percent Of The Speed Of Light

A UK team of astronomers report the first detection of matter falling into a black hole at 30 percent of the speed of light, located in the center of the billion-light year distant galaxy PG211+143.

Using data from the European Space Agency’s X-ray observatory XMM-Newton to observe the black hole, astronomers looked at X-ray spectra (where X-rays are dispersed by wavelength) from the galaxy PG211+143 located more than one billion light years away in the direction of the constellation Coma Berenices, and is a Seyfert galaxy.

The XMM-Newton spacecraft. Credit: ESA

“The galaxy we were observing with XMM-Newton has a 40 million solar mass black hole which is very bright and evidently well fed. Indeed some 15 years ago we detected a powerful wind indicating the hole was being over-fed,” Prof. Ken Pounds of the University of Leicester, from the University of Leicester’s Department of Physics and Astronomy, said in a press release.

“While such winds are now found in many active galaxies, PG1211+143 has now yielded another ‘first,” with the detection of matter plunging directly into the hole itself.”

“We were able to follow an Earth-sized clump of matter for about a day, as it was pulled towards the black hole, accelerating to a third of the velocity of light before being swallowed up by the hole.”

The researchers found the spectra to be strongly red-shifted, showing the observed matter to be falling into the black hole at the enormous speed of 30 per cent of the speed of light, or around 100,000 kilometers per second.

The gas has almost no rotation around the hole, and is detected extremely close to it in astronomical terms, at a distance of only 20 times the hole’s size (its event horizon, the boundary of the region where escape is no longer possible).

The observation agrees closely with recent theoretical work, also at Leicester and using the UK’s Dirac supercomputer facility simulating the ‘tearing’ of misaligned accretion discs. This work has shown that rings of gas can break off and collide with each other, cancelling out their rotation and leaving gas to fall directly towards the black hole.

A further implication of the new research is that ‘chaotic accretion’ from misaligned discs is likely to be common for supermassive black holes. Such black holes would then spin quite slowly, being able to accept far more gas and grow their masses more rapidly than generally believed, providing an explanation for why black holes which formed in the early Universe quickly gained very large masses.

Results are published in Monthly Notices of the Royal Astronomical Society.